title: Imaging the membrane protein bacteriorhodopsin with the atomic force microscope.
abstract: The membrane protein bacteriorhodopsin was imaged in buffer solution at room temperature with the atomic force microscope. Three different substrates were used: mica, silanized glass and lipid bilayers. Single bacteriorhodopsin molecules could be imaged in purple membranes adsorbed to mica. A depression was observed between the bacteriorhodopsin molecules. The two dimensional Fourier transform showed the hexagonal lattice with a lattice constant of 6.21 +/- 0.20 nm which is in agreement with results of electron diffraction experiments. Spots at a resolution of approximately 1.1 nm could be resolved. A protein, cationic ferritin, could be imaged bound to the purple membranes on glass which was silanized with aminopropyltriethoxysilane. This opens the possibility of studying receptor/ligand binding under native conditions. In addition, purple membranes bound to a lipid bilayer were imaged. These images may help in interpreting results of functional studies done with purple membranes adsorbed to black lipid membranes.
authors.affiliation: Department of Physics, University of California, Santa Barbara 93106.
authors.forename: H J
authors.initials: HJ
authors.lastname: Butt
authors.forename: K H
authors.initials: KH
authors.lastname: Downing
authors.forename: P K
authors.initials: PK
authors.lastname: Hansma
mesh_terms: D000327:Adsorption; D000538:Aluminum Silicates; D001436:Bacteriorhodopsins / Q000737:chemistry / Q000378:metabolism / Q000648:ultrastructure*; D004577:Electron Probe Microanalysis / Q000295:instrumentation / Q000379:methods; D005293:Ferritins / Q000378:metabolism; D005898:Glass; D008051:Lipid Bilayers; D011485:Protein Binding
chemical_list: D000538:Aluminum Silicates; D008051:Lipid Bilayers; D001436:Bacteriorhodopsins; D005293:Ferritins; C011934:mica